LCS of a mobile communication network is to obtain the location information of a target UE by means of positioning technique, where the target UE refers to a target UE to be positioned in a mobile communication network and the location information may be the geographical information expressed in the form of latitude and longitude data or the location information with reference to local streets. The location information obtained by LCS system may be provided to the target UE for self-positioning, or to the communications system itself for area-specific charging or operation and maintenance, or to other clients, for instance agencies or individuals, that request for the location information of the target UE for use of value-added services. Therefore, LCS has wide applications in many fields such as emergency aid, vehicle navigation and intelligent traffic system, scheduling and team management, mobile yellow page inquiry, and enhanced network performance etc. In the Third Generation Partner Project (3GPP), specifications on LCS as well as the functional mode, structure, state description, and message flow of the LCS system have been proposed.
FIG. 1 is a schematic diagram showing the logical structure implementing LCS. As shown in FIG. 1, Applicant 101 requests the location information of Target UE 103 through Network 102 containing LCS system. Network 102 containing LCS system makes a legitimate authentication of Applicant 101 to check whether Target UE 103 permits Applicant 101 to request for its location information. If Applicant 101 passes the legitimate authentication of Network 102 containing LCS system, Network 102 locates Target UE 103 and provides Applicant 101 with the location information of Target UE 103; otherwise, Network 102 containing LCS system refuses the request from Applicant 101 for the location information of Target UE 103. Applicant 101 may comprise applicants and LCS clients. Said LCS client refers to software or hardware entity for obtaining the location information of one or more target UEs 103, which is interfaced with Network 102 containing LCS system. Said applicant refers to an LCS application client for requesting the location information of a target UE, such as an agency or an individual, which is the initiator of a location request. While LCS client can also be an applicant at the same time.
Functional entities for implementing location service in LCS system include Gateway Mobile Location Center (GMLC), subscribers' data storage server (HLR/HSS), Core Network (CN), and Radio Access Network (RAN). Wherein, GMLC may further include Requesting-GMLC (R-GMLC), Home-GMLC (H-GMLC), and Visited-GMLC (V-GMLC). R-GMLC refers to the GMLC in the network containing LCS system, which receives the location request for the target UE from an applicant, H-GMLC refers to the GMLC in the network containing LCS system, to which the target UE belongs, and V-GMLC refers to the GMLC in the network containing LCS system, which is currently visited by the target UE, that is, the GMLC in the network where the target UE currently locates. Wherein, R-GMLC, H-GMLC, and V-GMLC may be one physical entity.
At present, in 3GPP specifications, the Deferred Location Request Procedure for the change of area event and the implementation are provided. Said location request message of area variation class refers to the message in condition that the applicant designates in advance the target area and events for triggering location reports, for instance, a location report is requested to be reported to the applicant when the target UE enters, leaves, or is located at the designated target area. Said LCS system sends to the target UE the information about the designated target area and events for triggering location reports, and the target UE saves the information and initiates at the same time the appropriate application program. When the application program detects the occurrence of an event for triggering a location report, for instance, when the target UE has entered, left, or located in the designated target area, the target UE will report to the LCS system a location report, and the LCS system will forward the location report to the appropriate applicant, informing the corresponding applicant that the event designated for triggering a location report has occurred. In addition, the applicant may also designate the number of location reports required to be reported by the target UE, for instance, only one location report should be reported, or designate a valid period of time in which the target UE should periodical report location reports. In summery, with area variation class location requests, an applicant is able to define conveniently some LCSs with track monitoring function, for instance, child tracking and pet tracking, which make LCS be widely used for track monitoring.
FIG. 2 shows the message interaction in the processing of area variation class location request in the prior art. As shown in FIG. 2, the message interaction in the processing of area variation class location request comprises the steps of:
Step 201: the applicant sending to R-GMLC an LCS Service Request, which carries the identity of a target UE, designated target area, and events for triggering location reports, wherein the events for triggering location reports may comprise: reporting a location report when the target UE enters, leaves, or locates in the designated target area. The LCS Service Request may carry the valid time period of the LCS Service Request as well, for instance, the starting time and ending time, and the number of location reports reported by the target UE requested by the LCS Service Request. If a plurality of location reports is required, the LCS Service Request will also need to carry the time interval among the periodical reported location reports. This LCS Service Request is then the area variation class location request as mentioned above.
Step 202: after receiving the LCS Service Request, R-GMLC forwarding this LCS Service Request to H-GMLC, which makes a legitimate authentication for the applicant to determine whether the target UE permits the LCS system to provide this applicant with the location information of the target UE. If the applicant passes the legitimate authentication, HGMLC sending to V-GMLC the LCS Service Request; otherwise, H-GMLC returning to R-GMLC an authentication failed acknowledgment (Ack), R-GMLC refusing the area variation class location request for the target UE initiated by the applicant and ending the current processing of the area variation class location request.
Step 203: V-GMLC, after receiving the LCS Service Request, converting the designated target area carried by said request to a geographical identity identifiable to the network and sending to CN a Provide Subscriber Location request, which carries the identity of the target UE, the converted designated target area expressed in the network geographic format, and events for triggering location reports. Corresponding to the information carried in the LCS Service Request, this Provide Subscriber Location request may carry the number of the location reports reported as well, and if a plurality of location reports is required, the time interval among the periodically reported location reports is also carried.
Step 204: CN, when detecting the target UE is in the idle mode, initiating a paging for the target UE, and making authentication and ciphering for the target UE to judge whether the target UE is a legitimate network device. Furthermore, CN sending to the target UE a privacy verification notification, notifying the target UE that an applicant is requesting for its location information, and the target UE itself verifying whether to permit the LCS system to provide the applicant with the location information of the target UE.
Steps 205˜206: CN sending to the target UE via RAN a Location Area Event Invoke request, and the information carried in the Location Area Event Invoke request is corresponding to the information carried in the LCS Service Request. After receiving the Location Area Event Invoke request, the target UE starting the relevant application program in itself, monitoring the occurrence of the events for triggering location reports, and sending to CN a Location Area Event Invoke Ack, notifying CN that the current location request has been accepted and properly handled.
Steps 207˜210: after receiving the Location Area Event Invoke Ack, CN sending to V-GMLC a Provide Subscriber Location Ack, notifying V-GMLC that the current area variation class location request has been accepted. After receiving the Provide Subscriber Location Ack, V-GMLC sending to H-GMLC an LCS Service Response, notifying H-GMLC that the current area variation class location request has been accepted. After receiving the LCS Service Response, H-GMLC sending to R-GMLC the LCS Service Response, notifying R-GMLC that the current area variation class location request has been accepted. After receiving the LCS Service Response, R-GMLC sending to the applicant the LCS Service Response, notifying the applicant that the current area variation class location request has been accepted by the target UE.
Steps 211˜212: an event triggering a location report occurs, that is, the target UE enters, leaves, or locates in the designated target area, and the target UE sending via RAN a Location Area Event Report to CN that covers the designated target area, notifying CN that an event triggering a location report has occurred.
Steps 213˜214: after receiving the Location Area Event Report, CN sending a Subscriber Location Report to V-GMLC that covers the designated target area, notifying the V-GMLC that the event triggering a location report of the target UE has occurred. After receiving the Subscriber Location Report, V-GMLC sending to CN a Subscriber Location Report Ack, notifying CN that the Subscriber Location Report sent by CN has been received. At this moment, CN may generate a corresponding billing record for the current location request.
Steps 215˜218: after sending the Subscriber Location Report Ack to CN that covers the designated target area, V-GMLC sending to H-GMLC an LCS Service Response, notifying H-GMLC that an event triggering a location report of the target UE has occurred. After receiving the LCS Service Response, H-GMLC making authentication (privacy check) for the applicant to ensure that the location information of the target UE provided to the applicant is permitted under the authorization for this applicant. After the applicant passes the authentication, H-GMLC sending to R-GMLC an LCS Service Response, notifying R-GMLC that the event triggering a location report of the target UE has occurred. After receiving the LCS Service Response, R-GMLC sending to the applicant an LCS Service Response, notifying the applicant that the event triggering a location report of the target UE has occurred. Said V-GMLC in steps 211˜218 refers to GMLC where the target UE currently locates and which is able to cover the target area, it can be the same GMLC as V-GMLC said in steps 202˜210, or a different GMLC from V-GMLC said in steps 202˜210. Likewise, CN said in steps 211˜218 refers to CN where the target UE currently locates and which is able to cover the target area, it can be the same CN as said in steps 202˜210, or a different CN from that in steps 202˜210.
If an area variation class location request carries the interval among the periodically reported location reports and the number of the location reports, then the interval among the location reports reported by the target UE to the CN that covers the designated target area can not be smaller than the interval among the area variation class location requests, and the total number of location reports can not exceed the number required in the area variation class location request. The processing procedure of reporting each location report is basically the same as the above process shown in steps 211˜218.
As can be seen from the above message interactive process of area variation class location request defined by the 3GPP specifications, in step 212, when the target UE detects that an event triggering a location report has occurred, it will send via RAN a Location Area Event Report to CN that covers the designated target area, notifying CN that an event triggering a location report has occurred; in step 213, however, when receiving the Location Area Event Report, CN will not return to the target UE a corresponding response to notify the target UE that the Location Area Event Report sent by the target UE has been successfully received, but send to V-GMLC a Subscriber Location Report to notify V-GMLC that the event triggering a location report of the target UE has occurred. In the subsequent process CN will not return to the target UE a corresponding response either, which results in that the target UE can not determine whether CN that covers the designated target area has received the Location Area Event Report, increasing the uncertainty in the implementation of the LCS.
Moreover, as there is difference in the supporting capability of CNs in the network for LCS, for example some CNs are capable of supporting the area variation class location request, while others are not. CNs not supporting the processing of area variation class location requests may directly discard such location reports as it cannot identify the report when receiving a location report sent by the target UE. Thus, since in the present processing procedure there is no step of CN returning to the target UE a corresponding response, the target UE is unable to learn whether the reported location report has been properly processed by CN or discarded by CN.
In addition, there are other reasons that leads to the loss of the location reports reported to CN by the target UE, for instance, when the message is transferred via a wireless channel, the message may be lost due to instable radio signaling. As there is no mechanism by which CN returns a corresponding response to the target UE, the target UE will not know whether CN has properly received the location report currently reported. Furthermore, in the prior art the target UE makes no more reporting of the location report after one time of reporting to CN. If the location report reported is lost, even that an event triggering a location report that is designated by the applicant has occurred, the LCS system will not return any location reports of the target UE to the corresponding applicant, since CN has not received a location report of the target UE, which leads to a failure in the middle of the current processing procedure. Thus, the applicant can not properly receive the location report reported by the target UE, which adds uncertainty in the implementation of LCS.
Apart from the above description, there are some services as Advice of Charge Charging (AoCC) for charging, making use of the target UE, as well as Advice of Charge Information (AoCI) for providing the charging information, making use of the target UE. In accordance with the processing procedure of the prior art, as there is no mechanism for CN returning a corresponding response to the target UE, the current service will be charged right after the target UE has reported the location report, but if the LCS system does not receive this location report at this time due to some abnormal reasons, a charging error for the target UE may occur.